Server 2016 guest not detecting drive as thin provisoned

[compwizpro]

Hello,

I apologize if this question was asked earlier in advance.

We have a newly configured VxRail all flash appliance running ESXi 6.7 build 13004448.  I have deployed a new server 2016 guest from a template with hardware version v14 and latest vmware tools installed.  The VM as well as the template have the default vsan storage policy applied with object space reservation set to 0 - Thin.

When I look in the windows guest under optimize drives, I see all the drives registering as Hard Disk Drive and not Thin Provisioned.  I have this same configuration running on other non-vxrail storage minus the storage policy and the guest detects disk as thin provisioned without issue.

Is there a setting I'm missing or a gotcha with running this configuration on vsan?  I followed the article VMware Knowledge Base  regarding OVA/OVF deployment in the web console but it didn't find any policies configured for thick and I am not deploying from OVF / OVA.

Thanks for the help!

[compwizpro · Accepted solution]

After some search and other help, I was able to figure this out and it turned out to be quite simple.  By default, unmap is not enabled on vSAN.  I had to enable it on for the cluster running the command "esxcfg-advcfg -s 1 /VSAN/GuestUnmap" on one of the esx hosts.  After that and rebooting one of the VMs, it recognized the virtual disks as thin.